DE102014216213B4 - METHODS AND SYSTEMS FOR REPORTING WATER TO AN OXYGEN SENSOR BASED ON POWER CONSUMPTION OF A SENSOR HEATER - Google Patents

Abstract

An engine method, comprising: indicating an amount of water at an oxygen sensor disposed in an engine intake based on a transient increase in power consumption from a heating element of the oxygen sensor, wherein the amount of water at the oxygen sensor is indicated when the power consumption is above a threshold amount a baseline power consumption level increases.

Description

Engine systems may use recirculation of exhaust gas from an engine exhaust system to an engine intake system, a process referred to as exhaust gas recirculation (EGR), to reduce regulated emissions. For example, a turbocharged engine system may include a low pressure (LP) EGR system that recirculates exhaust gas from the exhaust system to the intake passage upstream of a turbocharger compressor. An intake oxygen sensor (IAO2) may be located in the engine intake downstream of the compressor and an intercooler to provide an indication of EGR flow based on measured intake air water content.

the DE 10 2014 215 995 A1 , DE 10 2011 002 553 A1 and DE 10 2012 200 062 A1 are in a similar technical field as the present invention. So affects the DE 10 2014 215 995 A1 a method and system for estimating water storage in a charge air cooler. the DE 10 2011 002 553 A1 relates to an internal combustion engine with a cylinder, an intake system including intake line for supplying the cylinder with charge air, an exhaust line, an exhaust gas turbocharger including exhaust gas recirculation (including recirculation line). A sensor for detecting charge air components is arranged downstream of a junction of the return line. the DE 10 2012 200 062 A1 refers to an internal combustion engine in which an oxygen sensor for detecting an exhaust gas recirculation rate is arranged in the air intake tract.

The present inventors have recognized various problems associated with the above system. In particular, intake oxygen sensor (IAO2) measurements for determining exhaust gas recirculation (EGR) in low pressure EGR vehicle systems may give an inaccurate indication of EGR flow if water from another source contacts the IAO2. For example, if the IAO2 is located downstream of the charge air cooler (CAC), condensate formed on the CAC may exit the CAC and splash against the IAO2. This allows the IAO2 to measure a higher water concentration than can actually be attributed to the EGR water vapor content in the intake air. A higher EGR flow rate than the actual EGR flow rate may then be indicated based on the output of the IA02 sensor. In some examples, use of this inaccurate EGR measurement may trigger diagnostic routines as well as inaccurate adjustment of spark timing or other combustion parameters.

Accordingly, it is an object of the present invention to provide an engine method and system for an engine which can address the above problems.

To solve this problem, a motor method according to claims 1 and 10 and a system according to claim 18 are proposed. Advantageous developments of the invention are the subject matter of the dependent claims.

In one example, the issues described above may be addressed by a method for indicating water at an oxygen sensor disposed in an engine intake based on a transient increase in power consumed by a heating element of the oxygen sensor. In particular, the oxygen sensor may be located downstream of a charge air cooler (CAC). If water comes into contact with the oxygen sensor, the power consumption of the heater may increase. Indicating water at the oxygen sensor may include indicating an amount of water at the oxygen sensor based on the magnitude of the transient increase in power consumed by the heating element. For example, if the power consumption of the heater element continues to increase above a baseline power consumption level, the amount of water indicated on the oxygen sensor may increase. One or more of spark timing and position of an intake throttle may be adjusted in response to an indication of water at the oxygen sensor. Additionally, in response to an indication of water at the oxygen sensor, the EGR diagnostic and/or the oxygen sensor heater diagnostic may be disabled. In one example, disabling EGR diagnostics may include disabling engine operating parameter adjustments based on EGR flow estimates, where the EGR flow estimates are based on oxygen sensor output. In this way, when water is indicated at the oxygen sensor, EGR flow estimates cannot be used to adjust spark timing or other combustion parameters or to trigger diagnostic routines. As a result, combustion stability and engine control accuracy can be increased. Further, adjusting intake throttle and/or spark timing while water is indicated at the oxygen sensor may reduce combustion instability due to engine water ingestion.

• 1 ist ein schematisches Diagramm eines als Beispiel dienenden Motorsystems mit einem stromabwärts eines Ladeluftkühlers angeordneten Sauerstoffsensor.
• 2 ist ein Flussdiagramm eines Verfahrens zur Angabe von Wasser an einem Sauerstoffsensor und zum Einstellen von Motorbetriebsbedingungen ansprechend auf die Wasserangabe.
• 3 ist eine Graphik als Beispiel dienender Motorbetriebsparametereinstellungen auf der Grundlage an einem Einlasssauerstoffsensor angegebenen Wassers.

It should be noted that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not intended that they or identifies essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

• 1 12 is a schematic diagram of an example engine system with an oxygen sensor located downstream of a charge air cooler.
• 2 12 is a flow chart of a method for indicating water at an oxygen sensor and adjusting engine operating conditions in response to the water indication.
• 3 Figure 12 is a graph of example engine operating parameter adjustments based on water indicated at an intake oxygen sensor.

The following description relates to systems and methods for indicating water at an oxygen sensor based on power consumption of a heater element of the oxygen sensor. In particular, the oxygen sensor may be located in an engine intake downstream of a charge air cooler (CAC) of an engine system, such as the engine system 1 be arranged. As such, the oxygen sensor may be referred to herein as an intake oxygen sensor (IAO2). When water (e.g., water droplets) comes into contact with the IAO2, the power consumption of the heating element (e.g., a heater) of the IAO2 may increase to maintain a desired temperature of the IAO2. If the power consumption increases above a baseline power consumption level by a threshold amount, water may be indicated at IAO2. 2 FIG. 12 shows a method for adjusting engine operation based on power consumption of the IAO2 heater. In particular, an engine controller may adjust engine operating parameters and/or disable engine diagnostics in response to a water indication. For example, when water comes into contact with the IAO2, the accuracy of exhaust gas recirculation (EGR) flow estimates based on the IAO2 output may decrease, resulting in lower engine control accuracy. Accordingly, in one example, the engine controller may disable engine operating parameter adjustments in response to EGR flow estimates in response to a water indication. If water is indicated on the IAO2, the combustion stability of the engine can also be reduced when the water is absorbed. Accordingly, in another example, the engine controller may adjust intake manifold airflow and/or spark timing in response to a water indication on IAO2 to increase combustion stability during water ingestion. Example engine operating parameter settings based on IA02 heater power consumption are at 4 shown.

1 1 is a schematic diagram of an example engine 10 that may be included in a propulsion system of an automotive vehicle. The engine 10 is shown with four cylinders or combustion chambers 30 . However, other numbers of cylinders may be used in accordance with the present disclosure. The engine 10 may be controlled at least in part by a control system including a controller 12 and by input from a vehicle operator 132 via an input device 130 . In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Each combustion chamber (e.g., cylinder) 30 of engine 10 may include combustion chamber walls with a piston (not shown) disposed therein. The pistons may be coupled to a crankshaft 40 such that reciprocating motion of the piston is translated into rotary motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system 150 . Further, a starter may be coupled to the crankshaft 40 via a flywheel to enable the engine 10 to start. The crankshaft 40 can also be used to drive an alternator (in 1 not shown) can be used.

Engine output torque may be transferred to a torque converter (not shown) to drive the automatic transmission system 150 . Further, one or more clutches, including a forward clutch 154, may be engaged to propel the motor vehicle. In one example, the torque converter may be referred to as a component of transmission system 150 . Further, the transmission system 150 may include multiple speed clutches 152 that may be engaged on demand to activate multiple fixed transmission gear ratios. In particular, by adjusting the engagement of the plurality of speed clutches 152, the transmission may be shifted between a higher gear (ie, a gear with a lower gear ratio) and a lower gear (ie, a gear with a higher gear ratio). In doing so, the gear ratio difference allows for a lower torque multiplication across the transmission when in higher gear, while allowing higher torque multiplication across the transmission when in lower gear. The vehicle may have four available gears, with transmission gear four (the fourth transmission gear) being the highest gear available and transmission gear one (the first transmission gear) being the lowest gear available. According to other embodiments, the vehicle may have more or less than four gears available. A controller may change the transmission gear (eg, upshift or downshift the transmission gear) to adjust the amount of torque transferred through the transmission and torque converter to the vehicle wheels 156 (ie, engine shaft output torque).

When the transmission shifts to a lower gear, engine speed (Ne or RPM) increases, increasing engine airflow.

Intake manifold vacuum created by the spinning engine may be increased at the higher RPM. In some examples, a downshift may be used to increase engine airflow and purge accumulated condensate in a charge air cooler (CAC) 80 .

The combustion chambers 30 may receive intake air from the intake manifold 44 and expel combustion gases via an exhaust manifold 46 to an exhaust passage 48 . Intake manifold 44 and exhaust manifold 46 may selectively communicate with combustion chamber 30 via respective intake valves and exhaust valves (not shown). According to some embodiments, the combustion chamber 30 may include two or more intake valves and/or two or more exhaust valves.

Fuel injectors 50 are shown coupled directly to combustion chamber 30 for injecting fuel directly therein in proportion to the pulse width of signal FPW received from controller 12 . In this manner, the fuel injector 50 provides so-called direct injection of fuel into the combustion chamber 30, however, it should be understood that port fuel injection is also possible. Fuel may be delivered to fuel injector 50 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail.

In a process called ignition, the injected fuel is ignited by known ignition means such as a spark plug 52, resulting in combustion. The spark ignition timing can be controlled so that ignition occurs before (advance) or after (retard) the time specified by the manufacturer. For example, spark timing may be retarded from maximum braking torque (MBT) timing to control engine knock or advanced under high humidity conditions. In particular, the MBT timing can be advanced to account for the slow burn rate. In one example, ignition may be delayed during onset. According to an alternative embodiment, compression ignition may be used to ignite the injected fuel.

The intake manifold 44 may receive intake air from an intake passage 42 . The intake passage 42 has a throttle 21 with a throttle plate 22 for regulating flow to the intake manifold 44 . In this particular example, the position (TP) of the throttle plate 22 may be changed by the controller 12 to enable electronic throttle control (ETC). In this way, the throttle 21 can be operated to vary the intake air provided to the combustion chambers 30 . For example, the controller 12 may adjust the throttle plate 22 to increase an opening of the throttle 21 . By increasing the opening of the throttle 21, the amount of air supplied to the intake manifold 44 can be increased. In an alternate example, the opening of the throttle 21 may be reduced, or it may be fully closed to shut off air flow to the intake manifold 44 . According to some embodiments, additional chokes may be present in the intake passage 42, such as a choke upstream of a compressor 60 (not shown).

Further in accordance with the disclosed embodiments, an exhaust gas recirculation (EGR) system may direct a desired portion of exhaust gas from exhaust passage 48 to intake passage 42 via an EGR passage, such as high pressure EGR passage 140 . The amount of EGR provided to the intake passage 42 may be altered by the controller 12 via an EGR valve, such as the high pressure EGR valve 142 . Under some conditions, the EGR system can be used to regulate the temperature of the air-fuel mixture within the combustion chamber. 1 14 shows a high pressure EGR system wherein EGR is routed from a location upstream of a turbine of a turbocharger through EGR passage 140 to a location downstream of a compressor of a turbocharger. 1 also shows a low pressure EGR system where the EGR is pumped from a location downstream of the Turbocharger turbine is routed through low pressure EGR passage 157 to a location upstream of a turbocharger compressor. A low pressure EGR valve 155 may control the amount of EGR provided to intake passage 42 . According to some embodiments, the engine may have both a high-pressure EGR system and a low-pressure EGR system, as shown in FIG 1 is shown. According to some embodiments, the engine may have either a low pressure EGR system or a high pressure EGR system. In operation, the EGR system can induce the formation of condensate from the compressed air, particularly when the compressed air is cooled by the charge air cooler, as described in more detail below.

The engine 10 may further include a compression device, such as a turbocharger or supercharger, including at least one compressor 60 disposed along the intake passage 42 . For a turbocharger, the compressor 60 may be at least partially driven by a turbine 62, such as via a shaft or other coupling arrangement. The turbine 62 may be positioned along the exhaust passage 48 . Various arrangements for driving the compressor can be provided. For a supercharger, the compressor 60 may be at least partially powered by the engine and/or an electric machine and may not include a turbine. Accordingly, the amount of compression provided to one or more cylinders of the engine via a turbocharger or supercharger may be altered by controller 12 .

According to the 1 1 embodiment, the compressor 60 may be primarily driven by the turbine 62. Turbine 62 may be powered by exhaust gases flowing through exhaust passage 48 . Accordingly, the driving motion of the turbine 62 can drive the compressor 60 . As such, the speed of the compressor 60 may be based on the speed of the turbine 62 . As the speed of the compressor 60 increases, more boost may be provided to the intake manifold 44 through the intake passage 42 .

Further, the exhaust passage 48 may include a wastegate 26 to divert exhaust from the turbine 62 . Additionally, the intake passage 42 may include a compressor shunt or recirculation valve (CRV) 27 configured to divert intake air around the compressor 60 . The wastegate 26 and/or the CRV 27 may be controlled by the controller 12 to open, for example, when a lower boost pressure is desired. For example, in response to a compressor surge or possible compressor surge event, the controller 12 may open the CRV 27 to reduce the pressure at the outlet of the compressor 60 . This can reduce or stop compressor surge.

The intake passage 42 may further include a charge air cooler (CAC) 80 (e.g., an intercooler) to reduce the temperature of the turbocharged or boosted intake gases. According to some embodiments, the CAC 80 may be an air-to-air heat exchanger. According to other embodiments, the CAC 80 may be an air-to-liquid heat exchanger. The CAC 80 can also be a variable volume CAC. Hot charge air (charged air) from the compressor 60 enters the inlet of the CAC 80 , cools while passing through the CAC and then exits to pass through the throttle 21 and then enters the engine intake manifold 44 . Ambient air flow from outside the vehicle may enter the engine 10 through a front end of the vehicle and flow through the CAC to assist in cooling the charge air. Condensate can form and accumulate in the CAC when the ambient air temperature decreases, or during humid and rainy weather conditions where the charge air is cooled below the water dew point temperature. If the charge air entering the CAC is boosted (e.g., boost pressure and/or CAC pressure greater than atmospheric pressure), condensate may form if the CAC temperature drops below the dew point temperature. If the charge air contains recirculated exhaust gases, the condensate can become acidic and corrode the CAC housing. In the case of water-to-air coolers, the corrosion can lead to leaks between the air charge, the atmosphere and possibly the coolant. Furthermore, if condensate accumulates in the CAC, it may be ingested by the engine during periods of increased flow. This can result in unstable combustion and/or engine misfire.

Having located in the intake passage 42 or in the engine intake. Here, the one or more oxygen sensors may be referred to as inlet oxygen sensors. According to the illustrated embodiment, an intake oxygen sensor (IAO2) 162 is positioned downstream of the CAC 80 in the engine intake. In one example, the IAO2 162 can be positioned at an outlet of the CAC 80 . As such, the IAO2 162 may be referred to herein as the CAC outlet oxygen sensor. As another example, the IAO2 162 may be downstream of the outlet of the CAC 80 im Intake manifold 44 are positioned. In another example, IAO2 may be positioned upstream of choke 21 and downstream of CAC 80 .

The IAO2 162 may be any suitable sensor for providing an indication of the oxygen concentration of the charge air (e.g., the air flowing through the intake passage 42), such as a linear oxygen sensor, an intake UEGO (universal or wide-range exhaust gas oxygen) sensor, a dual-state oxygen sensor etc. The IAO2 162 includes a heater or heating element configured to be activated to heat the IAO2 to its operating temperature. In particular, the IAO2 may have a target temperature, such as 800°C. In another example, the target temperature of IAO2 may be greater or less than 800°C. A closed loop control system of the IAO2 can then control the heating element to maintain the set temperature. For example, if the temperature of the sensor decreases below the set point, the heater may consume more power output to the sensor to increase the sensor temperature. Further details on the power consumption of the heating element to maintain a set temperature of IAO2 are discussed below.

The EGR dilution percentage of the intake charge at a given time (e.g., the ratio between burned gases and air in an intake passage of the engine) can be derived from the output of IAO2 162 . In particular, when the intake oxygen concentration is reduced, an increase in EGR may be inferred because the presence of EGR may dilute the oxygen in the intake flow at the IAO2 sensor 162 . Conversely, when the intake oxygen concentration increases, a decrease in EGR due to the EGR reduction can be inferred. The controller 12 may estimate the EGR flow percentage dilution based on feedback from the IAO2 162 . Further, the controller 12 may then estimate an EGR amount or EGR flow rate based on the feedback from the IAO2 162 . In some examples, the controller 12 may then adjust one or more of the high pressure EGR valve 142, the low pressure EGR valve 155, the throttle 21, the CRV 27, and the wastegate 26 to provide a desired EGR dilution percentage of the intake charge and /or to achieve the desired EGR flow rate.

The control device 12 is in 1 is shown as a microcomputer having a microprocessor unit 102, input/output ports 104, an electronic storage medium for executable programs and calibration values, shown in this particular example as a read-only memory chip 106, random access memory 108, holding memory 110, and a data bus. Controller 12 may receive various signals from sensors coupled to engine 10 to perform various functions for operating engine 10 . In addition to the signals discussed above, these signals may include a measurement of induced mass airflow from MAF sensor 120, engine coolant temperature (ECT) from temperature sensor 112, which is shown schematically at a location within engine 10, a profile ignition pickup signal (PIP) from a Hall effect sensor 118 (or other type) coupled to crankshaft 40, including throttle position (TP) from a throttle position sensor, as discussed, and manifold absolute pressure signal MAP from sensor 122, as discussed. A motor speed signal RPM may be generated by the controller 12 based on the signal PIP. Manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of vacuum or pressure in intake manifold 44 . It should be noted that various combinations of the above sensors can be used, such as a MAF sensor without a MAP sensor or vice versa. During stoichiometric operation, the MAP sensor may provide an indication of engine torque. Further, this sensor, along with the detected engine speed, can provide an estimate of the charge (e.g., air) inducted into the cylinder. In one example, the Hall effect sensor 118, which is also used as an engine speed sensor, may generate a predetermined number of equally spaced pulses every revolution of the crankshaft 40.

Other sensors that may send signals to the controller 12 include a temperature and/or pressure sensor 124 at an outlet of a charge air cooler 80, the IAO2 162, and a boost pressure sensor 126. There may also be other sensors, not shown, such as a sensing sensor the intake air velocity at the inlet of the charge air cooler, as well as other sensors. In some examples, the storage medium of read-only memory chip 106 may be programmed with computer-readable data representing instructions executable by microprocessor unit 102 for performing the methods described below, as well as other variations that are anticipated but not specifically listed. Example routines are described here in 2 described.

The system off 1 provides an engine system comprising an intake manifold with an intake throttle, a charge air cooler disposed upstream of the intake manifold, an oxygen sensor disposed at an outlet of the charge air cooler, the oxygen sensor having a heating element, and a controller having computer-readable instructions for indicating water at the oxygen sensor in response to an increase in power consumption of the oxygen sensor heater element above a threshold during a selection condition. The computer-readable instructions may further include instructions for adjusting engine operating conditions based on the indication of water at the oxygen sensor, the engine operating conditions including one or more of an opening of the intake throttle and ignition timing, the selection condition being an ambient humidity that is greater than a threshold , depends.

As described above, an intake oxygen sensor (IAO2) may be placed downstream of a CAC to determine the oxygen concentration of the intake air. In particular, the IAO2 sensor may be used to determine the EGR dilution percentage of the intake charge air and subsequently determine an estimate of the EGR flow. However, IAO2 measurements may give an inaccurate indication of EGR flow if water from another source contacts the IAO2. For example, as discussed above, condensate may form within the CAC and then be expelled therefrom. In this situation, the condensate can hit the IAO2 and cause the IAO2 to measure a higher water concentration than can actually be attributed to the water vapor content of the EGR in the intake air. The IAO2 sensor may then indicate an EGR flow rate that is higher than the actual EGR flow rate. In some examples, use of this inaccurate EGR measurement may trigger diagnostic routines such as EGR system diagnostics. Additionally, spark timing or other combustion parameters, such as injection timing, may be misadjusted in response to the EGR flow estimate.

As mentioned in the introduction above, the IAO2 has a heating element for maintaining an operating temperature of the sensor. If water comes into contact with or splashes against the IAO2, the temperature of the heating element may decrease. As a result, a closed loop temperature controller of the IAO2 increases the power supplied to the heating element to maintain the IA02 temperature at the setpoint temperature. Accordingly, an increase in heater power or heater power consumption may indicate that water is present at IAO2. This, in turn, can indicate water is moving through the intake manifold and to the cylinders of the engine.

wobei ΔP die Änderung des Leistungsverbrauchs des Heizelements während des Sensorbetriebs ist, P_gemessen der gemessene Leistungsverbrauch des Heizelements ist und P_Grund der Grundlinienleistungsverbrauch des Heizelements ist (ohne dass Wasser in Kontakt mit dem Sensor steht). Falls ΔP größer als eine Schwellenleistung ist (beispielsweise eine Wasserspritzschwelle), kann Wasser am IAO2 angegeben werden. Die Schwellenleistung oder der Schwellenbetrag der Leistungserhöhung kann auf einer Wassermengenschwelle, welche die Genauigkeit von EGR-Schätzungen verringern kann, und/oder einer Wassermengenschwelle, welche die Verbrennungsstabilität verringern kann, beruhen.If the heater power consumption increases by a threshold amount, water may be indicated at IAO2 and in the intake manifold. In one example, a baseline power consumption value P _base may be determined during calibration of IAO2. In particular, the baseline power consumption of the IAO2 can be determined during a condition where no water in dry or humid air (e.g. under substantially dry conditions) is contacting the sensor. Then, during engine operation, if the power consumption of the heater element increases by a threshold amount above the baseline power consumption level, a controller (e.g., the 1 controller shown 12) Specify water on IAO2. This concept can be described with the following formula: $$\mathrm{\Delta }\text{P}={\text{P}}_{\text{measured}}-{\text{P}}_{\text{reason}},$$

where ΔP is the change in heater power consumption during sensor operation, P _measured is the measured heater power consumption, and P _baseline is the baseline heater power consumption (with no water in contact with the sensor). If ΔP is greater than a threshold power (e.g., a water splash threshold), water may be declared at IAO2. The threshold power or threshold amount of power increase may be based on a water amount threshold, which may reduce accuracy of EGR estimates, and/or a water amount threshold, which may reduce combustion stability.

Additionally, an amount of water at IAO2 or a rate of water in contact with IAO2 may be determined based on the amount of increase in power or power consumption of the heating element from the baseline power consumption level. For example, as ΔP increases, the amount of water and/or rate of water accumulation at IAO2 may also increase. Accordingly, as ΔP increases, the amount of water ingested by the engine may also increase. This can cause engine misfire and/or unstable combustion.

In response to an indication that there is water at the IAO2, the controller may disable engine system diagnostics and/or taking mitigating action in response to intake manifold water ingestion. In one example, the controller may disable the EGR system diagnostics in response to a water indication on the IAO2. For example, adjustments to EGR flow rate and/or combustion parameters may be temporarily disabled in response to EGR flow estimates until there is no water at IAO2 (e.g., power consumption has decreased below the threshold). In another example, the controller may disable the IA02 heater diagnostic in response to a water indication on the IAO2. For example, the increase in heater power consumption may result in indications of heater degradation and/or heater overcurrent readings. Accordingly, during water spray conditions at IAO2 (e.g., when ΔP is greater than the threshold), indication of IA02 degradation may be disabled. In yet another example, in response to a water indication on IAO2, airflow to the engine may be adjusted to control the rate of engine water ingestion below a rate that may cause engine misfire and/or engine unstable operation. In particular, throttle opening can be reduced to reduce airflow and the rate of water ingestion into the engine. The amount of throttle opening reduction may be based on the amount of water at the IAO2. As the amount of water at the IAO2 increases (e.g., as the heater power draw continues to increase above the baseline), the throttle opening may be reduced to a greater extent. In another example, in response to a water indication on the IAO2, the controller may adjust spark timing and/or change combustion parameters to account for the increased amount of water in the engine cylinders. In particular, the controller may adjust the ignition timing based on the amount of water estimated at IAO2.

In this way, an engine method may include indicating water at an oxygen sensor disposed in an engine intake based on a transient increase in power consumed by a heating element of the oxygen sensor. In one example, the oxygen sensor is located at an outlet of a charge air cooler. The method may further include disabling exhaust gas recirculation system diagnostics in response to an indication of water at the oxygen sensor. Additionally, the method may include temporarily disabling an oxygen sensor heater degradation indication in response to an indication of water at the oxygen sensor, the duration of the disablement depending on the rate of power increase. As a result, changes in heater power consumption may not trigger an indication of heater degradation when water is indicated on the oxygen sensor.

In one example, the indication of water includes indicating an amount of water at the oxygen sensor based on the transient increase in power consumed by the heating element. The method may further include adjusting a position of an intake throttle in response to the oxygen sensor indicating water to regulate the water ingestion rate below a threshold rate. In one example, the transient increase in power is due to a transient increase in power consumption rate. Adjusting the position of the intake throttle may include decreasing the opening of the intake throttle to reduce airflow through an intake manifold below the threshold rate, with the reduction in airflow increasing with an increasing amount of water at the oxygen sensor. In other words, as the amount of water at the oxygen sensor increases, the airflow may be decreased by a greater amount (e.g., the throttle opening may be decreased by a greater amount). Additionally, the ignition timing can be adjusted based on the amount of water at the oxygen sensor. For example, adjusting spark timing may include advancing spark timing when pedal position is increasing and retarding spark timing when pedal position is below a threshold position. In another example, indicating water may include indicating a water intake rate at the intake manifold based on the transient increase in power consumed by the heating element.

2 FIG. 200 shows a method for indicating water at an oxygen sensor and adjusting engine operating conditions in response to the water indication. In particular, the oxygen sensor may be an intake oxygen sensor installed in an intake of an engine near an outlet of a CAC (e.g. of the type shown in 1 illustrated inlet oxygen sensor 162) is arranged. In one example, the method 200 is defined by the in 1 shown control device 12 executable.

The method begins at 202 with estimating and/or measuring engine operating conditions. Engine operating conditions may include engine speed and load, pedal position, mass air flow, torque demand, EGR flow, oxygen sensor readings, CAC conditions (such as temperature and pressure), ambient temperature and pressure, etc. At 204, the method includes determining power consumption of a heater (eg, a heating element) of the intake oxygen sensor (IAO2). The method then includes, at 206, determining whether the difference between the measured power consumption and the baseline power consumption (e.g., ΔP) of the heating element is greater than a threshold. As discussed above, the threshold may be a threshold power or a threshold amount of power increase. The threshold may be based on a threshold increase in performance corresponding to a water amount threshold that may reduce the accuracy of EGR estimates by a certain percentage (e.g., 10%) and/or a water amount threshold that may reduce combustion stability.

If the difference between the measured power consumption and the baseline power consumption of the heater is not greater than the threshold, the method continues at 208 to determine the EGR based on the IA02 measurement (e.g., output). As described above, IA02 measurements may indicate EGR dilution percentage of intake air. This EGR dilution percentage can then be used to derive EGR flow. The method further includes activating the EGR system and IAO2 diagnostics at 208 . This allows the controller to adjust EGR combustion parameters (e.g., spark timing, injection timing, etc.) at 209 based on the determined EGR dilution percentage. Additionally, at 210, the method includes adjusting an EGR valve to deliver the desired EGR flow. The desired EGR flow may be based on the desired intake air dilution percentage, additional engine operating conditions, and/or the determined EGR flow.

Alternatively, if the difference between the measured power consumption and the baseline power consumption of the heater is greater than the threshold at 206, the method continues at 212 to indicate water at IAO2. Indication of water on the IAO2 can also include indication of water in the intake manifold and increased water ingestion by the engine. In response to the IAO2 indicating water, the controller may disable the EGR system diagnostics at 214 . As discussed above, disabling EGR system diagnostics may include disabling engine operating parameter adjustments based on EGR flow estimates, where the EGR flow estimates are based on IAO2 sensor readings. Additionally, at 214, the method may include disabling IAO2 diagnostics, which may indicate IAO2 heater degradation. For example, if IAO2 heater degradation is reported based on increased power consumption, no degradation may be reported while water is reported at IAO2. In this way, false heater degradation indications can be reduced.

At 216, the method includes determining the amount of water at IAO2 based on the difference ΔP between the measured power consumption and the baseline power consumption. As discussed above, as ΔP increases, the amount of water reported on IAO2 may increase. In another example, the method at 216 may additionally or alternatively include determining the water accumulation rate at IAO2 or the water ingestion rate at the intake manifold based on ΔP. Similarly, as ΔP increases, the water accumulation rate can also increase. At 218, the controller may adjust intake manifold airflow and/or spark timing based on the amount of water at IAO2. For example, the controller may adjust the opening of an intake throttle to control the rate of water ingestion at the intake manifold and into the engine. In one example, the controller may decrease throttle opening to decrease air flow to the engine. This allows intake manifold water to be ingested at a rate that can reduce engine misfire or combustion instability. In another example, the controller may adjust ignition timing to reduce combustion instability during water ingestion. For example, adjusting ignition timing during water ingestion may include advancing ignition timing as pedal position increases (e.g., during an onset). In another example, adjusting the ignition timing during water ingestion may include retarding the ignition timing when the pedal position is below a threshold position. The amount of spark retard or spark advance may be based on the amount of water determined at the IAO2. According to other embodiments, additional or alternative combustion parameters, such as injection timing, may be adjusted in response to ΔP and the amount of water at IAO2.

According to some embodiments, the method 200 may further address closing the EGR valve or reducing the opening of the EGR valve to reduce EGR flow corresponding to a water indication on the IAO2 at 212. Accordingly, in some examples, after 216 the method may include an additional step that includes adjusting the EGR flow based on the amount of water in the intake manifold (determined based on ΔP). Reducing the EGR flow can reduce the amount of extra water vapor entering the engine cylinders.

At 220, the method includes returning spark timing and throttle position to desired levels when power consumption of the heater (eg, a heating element) returns to P _base . The method at 220 may further include activating the EGR system and IAO2 heater diagnostics when heater power consumption returns to P _base . As such, EGR flow may be determined based on the IAO2 output, as described at 208 . EGR combustion parameters and EGR flow may then be adjusted based on the estimated EGR flow, as described at 209 and 210 .

In this manner, an engine method may include adjusting a turbocharger that compresses engine intake air, adjusting direct injection of fuel into the engine, cooling the compressed air in an intercooler, and adjusting engine operating conditions in response to power consumption of an oxygen sensor heater element in of the compressed air increases by a threshold amount above a baseline power consumption level with the oxygen sensor located downstream of the charge air cooler. Adjusting engine operating conditions may include one or more of disabling exhaust gas recirculation diagnostics and disabling an indication of oxygen sensor heater degradation. The method may further include estimating one or more of an amount of water and a rate of water ingestion at the intake manifold based on power consumption of the heating element, where the amount of water and the rate of water ingestion increase as power consumption increases. Adjusting engine operating conditions may additionally or alternatively include adjusting one or more of air flow to the intake manifold and spark timing based on one or more of water amount and water intake rate at the intake manifold.

In one example, the threshold amount is based on a water amount threshold that results in reduced accuracy of exhaust gas recirculation flow estimates or reduced combustion stability. Additionally, the baseline power consumption may be based on the power consumption of the heating element under dry conditions.

The method may further include enabling exhaust gas recirculation system diagnostics and determining exhaust gas recirculation flow based on an output of the oxygen sensor when power consumption of the heater is less than a threshold amount above the baseline power consumption level. The method may then also include adjusting EGR combustion parameters based on the determined EGR flow. In one example, an exhaust gas recirculation valve may be adjusted to deliver a desired exhaust gas recirculation flow, where the desired exhaust gas recirculation flow is based on engine operating conditions and the determined exhaust gas recirculation flow.

3 FIG. 12 shows a graphical example of adjusting engine operating parameters based on water indicated at an intake oxygen sensor. Specifically, graph 300 shows changes in IA02 output at 302, changes in heater (eg, heating element) power consumption at plot 304, changes in water determined at IAO2 at plot 306, changes in estimated EGR flow at plot 308, Changes in actual EGR flow on a plot 310, changes in pedal position (PP) on a plot 312, changes in ignition timing relative to MBT on a plot 314, changes in position of an EGR valve on a plot 316, changes in throttle opening at plot 318 and changes in air flow to the engine at plot 320 . As discussed above, the IAO2 is located downstream of the CAC in the inlet. In one example, the IAO2 can be placed at the outlet of the CAC. The IAO2 output may be oxygen concentration or estimated oxygen fraction in the charge air. The charge air EGR dilution percentage may be derived from this output and used to determine the estimated EGR flow at plot 308 . In addition, the water determined at the IAO2 may be the amount of water or the rate of water accumulation at the IAO2, where the amount of water and the rate of water accumulation are based on the power consumption of the heater.

Prior to time t1, the power consumption of the heater of IAO2 is around the baseline power consumption level P _base (plot 304). At this time, the estimated EGR flow and the actual EGR flow may be substantially the same (plots 308 and 310, respectively). At time t1, the power consumption of the heater begins to increase (plot 304). The IAO2 output (plot 302), the estimated EGR flow (plot 308), and the water determined at IAO2 (plot 306) may also increase after time t1. At time t2, the power consumption of the heater increases to an upper power threshold P _threshold (plot 304). The difference between _Pthreshold and _Preason may be a threshold amount 322 of power increase ( _e.g. , Pmeasured− _Preason >threshold amount). This allows a controller to indicate water on the IAO2. Due to the water coming into contact with the IAO2, the estimated EGR flow (plot 308) is higher than the actual EGR flow (plot 310) between times t2 and t3.

In response to a water indication at IAO2 at time t2, the controller may disable EGR system diagnostics and/or heater degradation indications. For example, the position of the EGR valve, as shown in 3 is maintained even though the estimated EGR flow (plot 308) has increased. Also, at time t2, in response to a water indication at IAO2, throttle opening may be decreased (plot 318) to decrease air flow to the engine (plot 320). Such a reduction in airflow can reduce the rate of water ingestion into the engine. In addition, the ignition timing can be adjusted in response to a water indication on the IAO2 (task 314). Because PP increases (plot 312) before time t2, spark timing may be advanced at time t2.

At time t3, the power consumption of the IAO2 heater decreases back to P _base (plot 304). In response, spark timing and throttle position are returned to desired levels. Further, EGR system diagnostics and IAO2 heater diagnostics (eg, indicating heater degradation based on power consumption) may be re-enabled. Here, after time t3, combustion parameters and EGR flow may be adjusted based on EGR flow estimates determined from the IAO2 output.

In this way, water may be indicated at an oxygen sensor located in an inlet based on the increased power consumption of a heating element of the oxygen sensor. The water specification may indicate possible water ingestion by the engine via the intake manifold. As discussed above, an engine controller may adjust engine operating parameters and/or disable EGR and IAO2 heater diagnostics when heater power consumption increases a threshold amount above a baseline power consumption level. As such, EGR flow estimates based on IAO2 may not be used to adjust combustion parameters and/or an EGR valve while water is indicated at IAO2. By indicating water at the oxygen sensor, a technical effect is achieved by adjusting engine operating parameters to increase engine control and combustion stability during conditions where water is ingested by the engine.

It should be noted that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The specific routines described herein may represent one or more of a number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and similar processing strategies. As such, various of the acts, operations, and/or functions discussed may be performed in the sequence shown, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is for convenience of illustration and description. One or more of the actions, operations, and/or functions depicted may be performed repeatedly depending on the particular strategy used. Further, the acts, operations, and/or functions described may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the engine control system.

It should be noted that the configurations and routines disclosed herein are exemplary in nature and that these specific embodiments are not to be considered as limiting because numerous variations are possible. For example, the above technology can be applied to V-6, 1-4, 1-6, V-12, opposed 4, and other types of engines. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and/or properties disclosed herein.

The following claims specify certain combinations and sub-combinations that are believed to be novel and non-obvious These claims may relate to "an" element or "a first" element or an equivalent thereof. These claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements and/or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are also intended to be included within the subject matter of the present disclosure.

Claims (18)

An engine method, comprising: indicating an amount of water at an oxygen sensor disposed in an engine intake based on a transient increase in power consumption from a heating element of the oxygen sensor, wherein the amount of water at the oxygen sensor is indicated when the power consumption is above a threshold amount a baseline power consumption level increases. engine procedure claim 1 , further comprising disabling exhaust gas recirculation system diagnostics in response to an indication of water at the oxygen sensor. engine procedure claim 1 , further comprising temporarily disabling an oxygen sensor heater degradation indication in response to an indication of water at the oxygen sensor, a duration of the disablement being dependent on a power increase rate. engine procedure claim 1 , further comprising adjusting the position of an intake throttle in response to the oxygen sensor indicating water to regulate a water ingestion rate below a threshold rate, wherein the transient power increase is based on a transient increase in a power consumption rate. engine procedure claim 4 wherein adjusting the position of the intake throttle comprises decreasing an opening of the intake throttle to reduce airflow through an intake manifold (44) below the threshold rate, the reduction in airflow increasing with an increase in the amount of water at the oxygen sensor. engine procedure claim 1 , further comprising adjusting the ignition timing based on the amount of water at the oxygen sensor. engine procedure claim 6 wherein adjusting the spark timing comprises advancing spark timing when a pedal position (PP) increases and retarding spark timing when the pedal position (PP) is below a threshold position. engine procedure claim 1 wherein indicating water comprises indicating a rate of water ingestion at an intake manifold (44) based on the transient increase in power consumed by the heating element. engine procedure claim 1 , wherein the oxygen sensor is arranged at an outlet of a charge air cooler (80). An engine method comprising the steps of: adjusting a turbocharger that compresses engine intake air, adjusting direct injection of fuel into the engine (10), cooling compressed air in an intercooler (80), and adjusting engine operating conditions in response to power consumption of a heating element of a oxygen sensor in the compressed air increases by a threshold amount above a baseline power consumption level, the oxygen sensor being located downstream of the charge air cooler (80). engine procedure claim 10 wherein adjusting engine operating conditions comprises one or more of disabling exhaust gas recirculation diagnostics and disabling an indication of oxygen sensor heater degradation. engine procedure claim 10 The further comprising estimating one or more of an amount of water and a rate of water intake at an intake manifold (44) based on power consumption of the heating element, wherein the amount of water and the rate of water intake increase as power consumption increases. engine procedure claim 12 wherein adjusting engine operating conditions comprises adjusting one or more of air flow to the intake manifold (44) and spark timing based on one or more of water quantity and water intake rate at the intake manifold (44). engine procedure claim 10 , wherein the threshold amount is based on a water amount threshold resulting in reduced accuracy of exhaust gas recirculation flow estimates or reduced combustion stability, and wherein the baseline power consumption level is based on heater power consumption under dry conditions. engine procedure claim 10 , further comprising activating exhaust gas recirculation system diagnostics and determining exhaust gas recirculation flow based on an output of the oxygen sensor when power consumption of the heater is less than a threshold amount above the baseline power consumption level. engine procedure claim 15 , further comprising adjusting exhaust gas recirculation combustion parameters based on the determined exhaust gas recirculation flow. engine procedure claim 15 , further comprising adjusting an exhaust gas recirculation valve to deliver a desired exhaust gas recirculation flow, wherein the desired exhaust gas recirculation flow is based on engine operating conditions and the determined exhaust gas recirculation flow. A system for an engine (10) comprising: an intake manifold (44) having an intake throttle, a charge air cooler (80) located upstream of the intake manifold (44), an oxygen sensor located at an outlet of the charge air cooler (80). wherein the oxygen sensor includes a heater element, and a controller having computer readable instructions for indicating an amount of water at the oxygen sensor in response to an increase in power consumption of the heater element of the oxygen sensor by a threshold amount above a baseline power consumption level.

Images